In the case of a suspected lung mass in a high risk patient for lung cancer, it is the current standard of care to send the patient for radical removal of the mass. Certain portions of these surgeries are made by Video Assisted Thoracotomy Surgery (VATS), which is a minimally invasive surgery, and invasive Thoracic Surgery. Obtaining accurate diagnosis in the least invasive means possible as quickly as possible is essential. During VATS, it is often very hard to recognize the suspected small lung masses during the procedure. VATS success is limited by the ability to visualize and palpate the nodule if it is less than 10 mm in size and if it is more than 5 mm from a pleural surface. Historically, in 63% to 82% of cases there is an inability to visualize or palpate a detected nodule. (1. Burdine, et al. CHEST 2002; 122:1467, 2. Suzuki, et al. CHEST 1999; 115:563). Minimally invasive surgery is becoming more and more popular and holds similar challenges to those seen in VATS when used in the abdominal cavity, the urogenital system or other parts of the body.
A lung mass (solitary pulmonary nodules (SPN) or other) in the periphery of the lungs that is identified by X-ray machine or CT must also be physically identified by the surgeon for removal. However, visual identification of the mass may often be difficult due to tissue obstructions, such as, when the nodule is buried deep in the lung tissue.
Lack of visual identification creates problems. In some instances, surgeons discover lesions during surgery that were not earlier identified by a referring physician or radiologist. In this case, the surgeon needs to decide which of the lesions is suspected to be cancerous. Therefore, to avoid mistakes, the surgeon typically removes a larger portion of the tissue, ensuring the entire lesion is removed but also increasing tissue trauma, the possibility of complications, patient suffering, and so forth. In other cases, lack of visual identification results in the excision of healthy tissue rather than the targeted lesion.
In other body cavities similar challenges are encountered since visibility and the means to identify specific pre-planned lesions as were identified by medical imaging, is often limited.
Most current methods for identifying masses and other such lesions and tissues may best be characterized as “from the outside to the inside,” and are often rather complex, invasive and risky. Such methods include, for example, manual identification (e.g., finger palpation through the rib cage), intrathorascopic ultrasound, transthoracic placement of an external wire, injecting solidifying liquids, dye injection, TC-99 injection, radiopaque markers such as barium or injectable coils, guidance by CT, intrathorascopic ultrasound, fluoroscopy-assisted thoracoscopic resection, etc.
There are current challenges with external beam radiation delivery due to the inability to see the tumor during treatment. Accurate alignment of sterotactic planning onto the patient, before the procedure, is required for accurate real-time tracking of the tumor. Additionally, tumor position in the lungs is changing as a result of the normal respiratory cycle, unpredictable baseline shifts and variable amplitude of respiratory rates. Consequently, an insufficient dose of radiation may be delivered due to its toxic effects on surrounding healthy lung tissue and may lead to failure to control tumor growth. Because of these challenges, fiducial markers are often used in soft tissue to guide focused-beam radiation treatment.
One of the major drawbacks to fiducial marker placement is delivery of the marker transthoracically. This approach can lead to pneumothorax or collapsed lungs because often the patients already have compromised lung function. In addition to the risk of pneumothorax there is also the complication of marker migration. Unlike the relatively static, homogeneous tissue of the prostate, the lung tissue moves significantly with the breathing cycle and is also porous and interlaced with airways. As a result, an implanted seed is prone to migrate, typically out of the channel formed during placement, and fall down an airway. Once in the airway, the seed will either settle in a distal portion of the lungs, or be coughed out.
Another potential application for marker or catheter placement within the lungs may be for the delivery of therapies such as brachytherapy, cryotherapy, or drug delivery through a deposited drug depot.
If an inert or active marker seed or temporary catheter migrates, the target is lost. If the therapy vehicle is expectorated, the treatment ends prematurely. Even worse, if the delivery vehicle migrates away from the target, therapy is administered to healthy tissue instead of a tumor, thereby damaging the healthy tissue and sparing the tumor.
There is a need for an improved identification device or marking device and method of introducing this device into the body. More specifically, there is a need for an identification device or marking device that: 1) can be placed within the location of interest or adjacent to it and permits identification of masses or other location of interest, through the surrounding tissues, 2) is minimally invasive, and 3) has a minimal damaging effect on the tissue to avoid complications.
There may also be a need for a method of extracting this device from the body in a minimally invasive manner.
There is also a need for anchoring an identification or therapeutic device or marking device within the body.
There is also a need for a method of communication or bringing between two tools, one from “inside out” and the other one from “outside in”. The first is the so called identification device or marking device and the second is the complementary counterpart, which is an assembly of detector device and interventional device, capable to identify the signal emitted by the identification device or marking device, thus, the precision in localization is achieved and the task can be performed with great confidence.
There is also a need for a marker or therapeutic seed that includes an anchoring mechanism that prevents the seed from migrating once positioned.